FINAL YEAR PROJECT REPORT

ON

DESIGN AND FABRICATION OF REGENERATIVE SHOCK ABSORBER

(DEC 2011-MAY 2012)

SUBMITTED FOR
THE PARTIAL FULFILMENT OF THE AWARD OF THE DEGREE OF B.TECH (MECHANICAL & AUTOMATION ENGINEERING)

Prepared by: SANDEEP MAHENDER SINGH RANA AMIT SHARMA DEEPAK JAKHAR MOHIT BANSAL 08-40517/ B. Tech ME 08-40498/B. Tech ME 09-40533/B.Tech ME 08-40491/B.Tech ME 08-40502/B. Tech ME

UNDER THE SUPERVISION OF MR. ANIL MALIK

HARYANA INSTITUTE OF TECHNOLOGY

ASODHA,BAHADURGARH

Affiliated to : MAHARISHI DAYANAND UNIVERSITY(ROHTAK)

CERTIFICATE
This is to certify that the Final year Project entitled, Design & Fabrication of REGENERATIVE SHOCK ABSORBER has been submitted to the Department of Mechanical Engineering of HARYANA INSTITUTE OF TECHNOLOGY, ASODHA,BAHADURGARH, by SANDEEP, MAHENDER SINGH RANA, AMIT SAHRMA, DEEPAK JAKHAR, MOHIT BANSAL for partial fulfillment of the award of degree, Bachelor of Technology in Mechanical Engineering. The work is a record of genuine work carried out by them under our guidance and supervision and fulfills all requirements for the submission of the thesis, which has required standard. The matter embodied in this dissertation has not been submitted in part or full to any other university or institute for the award of any degree or diploma.

Mr. Anil Malik

Project Guide Department of ME

Mr. Sachin Dahiya

H.O.D Department of ME

ACKNOWLEDGEMENT
We, the member of this project team would like to acknowledgement all those people and Organization for their help in accomplishment of this project. We would like to heartiest thanks to Mr.Anil Malik, Lec. in Mechanical Engineering Department of HARYANA INSTITUTE OF TECHNOLOGY, who supervised our project and taken burden for their constructive ideas to guide us for preparing this project. completing our project. Meanwhile, we are grateful to Dr.Vinay, Director, HARYANA INSTITUTE OF TECHNOLOGY, for their logistic support in our project. We would also thanks to Mr. Sachin Dahiya , Head Section, Mechanical Engineering Department, HARYANA INSTITUTE OF TECHNOLOGY, to allow us doing the project. We would also like to thanks to our parents and guardian for appreciations and encouragement. Also we would like to thanks to our colleague and well-wishers and all workshop staff Mechanical engineering laboratory for their valuable co-operation in manipulating the data during the fabrication of Regenerative Shock Absorber.

ABSTRACT

Design and Fabrication of Regenerative Shock Absorber

In this project, it has been attempted to generate electricity with the help of the shockers used in the vehicle. A regenerative shock absorber is a type of shock absorber that converts parasitic intermittent linear motion and vibration into useful energy, such as electricity. Conventional shock absorbers simply dissipate this energy as heat. When used in an electric vehicle or hybrid electric vehicle the electricity generated by the shock absorber can be diverted to its power train to increase battery life. In non-electric vehicles the electricity can be used to power accessories such as air conditioning. Several different systems have been developed recently, though they are still in stages of development and not installed on production vehicles. The system is controlled by an active mechanical and electronic system that optimizes the damping, providing a smoother ride than conventional shocks while generating electricity to recharge the batteries or operate electrical equipment.

CONTENTS

1.

GENERAL INTRODUCTION 7

1.1 1.2

Introduction 7

Background of Invention 8 1.2.1 Field of Invention 9 1.2.2 Description of The Related Art 9 1.2.3 Summary of Invention 11 1.3 Shock Absorber 13 1.3.1 Explanation 14 1.3.2 Description 14 1.3.3 Applications 14 1.3.4 Vehicle Suspension 15 1.3.5 Structure 16 1.3.6 Types of Shock Absorber 16 1.4 Spring 1.4.1 Theory 22 1.4.2 Uses 23 1.5 Alternator 24 1.5.1 History 1.5.2 Theory of Operation

21

24 25
5

1.6 Rack & Pinion 1.7 Battery 1.7.1 Principle of Operation 29 1.7.2 Categories of Batteries 31

27 29

2.

EXPERIMENTAL SETUP 32

2.1 Introduction ...32 2.2 Mechanical Components ...33

2.2.1 2.2.2
35 2.3.2

Shock Absorber Arrangement 33 Rack & Pinion arrangement 34

2.3 Electric Alternator Arrangement

Battery Arrangement 34

3.
3.1

DESIGNING 36

Introduction ...36 3.2 Selection of Shock Absorber 38 3.2.1 Shock Absorber Diameter 38
6

3.2.2 3.2.3 39

Piston & Rod Diameter 38 Shock Absorber Oil Specification

3.2.4 Thrust Force Calculation 42 3.2.5 Calculation of Total Energy 43 3.2.6 Flow Chart For Selection of Shocker 44 3.3 Design of Rack & Pinion 45 3.3.1 Module 45 3.4 Selection of Alternator

48

4. 5.

FABRICATION 49 CONCLUSION 50 REFERENCES

Chapter 1 General Introduction

A regenerative shock absorber is a type of shock absorber that converts parasitic intermittent linear motion and vibration into useful energy, such as electricity. Conventional shock absorbers simply dissipate this energy as heat. When used in an electric vehicle or hybrid electric vehicle the electricity generated by the shock absorber can be diverted to its power train to increase battery life. In non-electric vehicles the electricity can be used to power accessories such as air conditioning. Several different systems have been developed recently, though they are still in stages of development and not installed on production vehicles. The system is controlled by an active mechanical system that optimizes the damping, providing a smoother ride than conventional shocks while generating electricity to recharge the batteries or operate electrical equipment. During testing of a 6-shock truck, the MIT students found each shock absorber is able to generate up to an average of 1 kW on standard road, which is "enough power to completely displace the large alternator load in heavy trucks and military vehicles." If for some reason the electronics on the shocks fail, the fail-safe feature will have
8

the shocks act simply like a normal shock absorber.

1.1. Introduction

A=ALTERNATOR B=ROD TO CONNECT WHEEL C=RUBBER SPRING/COVER TO PROTECT DUST E=SHOCKER ROD AREA
9

D=RACK AND PINION GEAR ASSEMBLY G=WHEEL

F=ELECTRICITY OUT FOR BATTERY CHARGING

In the above structure, a modified design is shown for the shocker motion provided by Rack and Pinion Gear Assembly that generates power. The motor(generator) will operate clock and anti-clock to operate as it sense the pot holes or bumps on the road. The shocker rod activates the rack and pinion up and down motion that run the motor (generator) in clock and anti-clock motion.

1.2. BACKGROUND OF THE INVENTION

1.2.1. Field of the Invention The present invention relates to systems for converting reciprocative vertical axle vibrations occurring during operation of a vehicle into electrical energy, and for modifying the ride of the vehicle. In particular, the inventive system uses the same reciprocative electromagnetic transducer as both a generator and a shock absorber assistant, and a control system for switching between these two modes of operation. 1.2.2. Description of the Related Art Systems and devices for converting mechanical energy from reciprocal motion into electrical energy in vehicles are known, as are systems and devices for converting
10

electrical to mechanical energy. However, these systems typically are limited to one of these types of energy conversion rather providing both capabilities. Moreover, even when both of these types of conversion are present or suggested, no system for selectively switching between the two types and for modifying ride comfort, is provided or taught. U.S. Pat. No. 6,405,841, issued to Zeno on Jun. 18, 2002, teaches an electromagnetic shock absorber. U.S. Pat. No. 5,880,532, issued to Stopher on Mar. 9, 1999, teaches an electromagnetic generator for converting the energy released by a vehicle when the brakes are applied into electrical energy. U.S. Pat. No. 5,678,847 issued to Izawa et al. on Oct. 21, 1997, teaches an active vehicle suspension system using an electromagnetic actuator. U.S. Pat. No. 4,900,054, issued to Kessler on Feb. 13, 1990, teaches an electromagnetic vehicle suspension system using a battery for power. U.S. Pat. No. 4,793,263, issued to Basic et al. on Dec. 27, 1988, teaches an electromagnetic propulsion system for use on railsupported vehicle. U.S. Pat. No. 4,160,181, issued to Lichtenberg on Jul. 3, 1979, teaches an electrical generator for use on a vehicle that uses the eddy current effect. U.S. Pat. No. 3,941,402, issued to Yankowski et al., teaches an electromagnetic shock absorber that uses a linear transducer to provide electrical power to operate the shock absorber. Japanese Patent No. 6-315294 teaches a

11

linear oscillation actuator. Japanese Pat. No. 60-257757 teaches an electromagnetic generator. European Patent No. 616,412, published Sep. 21, 1994, teaches a reciprocative electromechanical transducer for use in vehicle suspension. The transducer is used both as an electrical generator and as a shock absorber. Vertical movement of the wheel assembly relative to the chassis is converted into electricity to charge the vehicle battery or energize electrical components in the vehicle. Although the patent mentions switching the device between electrical generating and shock absorbing functions, it lacks any details of this switching system. However, some details are provided regarding the conversion of mechanical to electrical energy using the particular structure of the transducer. There is a need for a system that provides the capability of utilizing otherwise wasted mechanical energy in the form of reciprocating vertical vehicle vibration and that can also modify vehicle riding comfort, including the capability of selecting between the two. None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed. Thus a system for selectively using converting axle vibration into electrical energy solving the aforementioned problems is desired. 1.2.3. SUMMARY OF THE INVENTION

12

The present invention is directed to a dual-use electromechanical energy transducer for a vehicle and a control system for selecting between two modes of operation: a current generating mode and a shock absorber assistant mode. In particular, the inventive system uses an electromagnetic transducer that can be selectively used to convert otherwise wasted mechanical movements in the form of vertical vibrations in a moving vehicle into electrical current for charging a battery. Alternatively, the transducer can be selectively used as an assistant for the shock absorbers to adjust the riding characteristics of the vehicle. The dual-use transducer includes one or more magnets that move in direct response to the vertical vibrations of the axle during use of the vehicle. The magnet or magnets move in close proximity to, and perpendicularly to, windings in a current-carrying coil in accordance with Faraday's Law that relates induced voltage produced in a coil with the rate of change of the magnetic field. In a generator mode of operation, the transducer can be used to produce electrical current in the coil by movement of the magnets. Alternatively, the transducer can be used as an assistant to existing shock absorbers when the coil is shorted, thereby resisting movement of the magnet or magnets. Accordingly, it is a principal object of the invention to provide a dual-use electromechanical transducer usable in a generator mode of operation for generating electrical energy and alternatively usable in a shock absorber
13

assistant mode of operation, and to a system for selecting between the two modes. It is an object of the invention to provide a dual-use electromechanical transducer that can be used simultaneously as a generator and a shock absorber. It is another object of the invention to provide a system for converting axle vibration into electricity in which the transducer produces a current which can charge a battery. It is a further object of the invention to provide a system for converting axle vibration into electricity in which the vehicle ride can selectively be altered when not being used to generate electricity. It is an object of the invention to provide improved elements and arrangements thereof for the purposes described which is inexpensive, dependable and fully effective in accomplishing its intended purposes. These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings.

1.3. Shock Absorber

A shock absorber in common parlance (or damper in technical use) is a mechanical device designed to smooth out or dampen a sudden shock impulse and dissipate kinetic energy. It is analogous to a resistor in an electric RLC circuit.
14

Shock absorber with internal reservoir. The components are: the rod (A), the piston with seals (B), the cylinder (C), the oil reservoir (D), the floating piston (E), and the air chamber (F).

1.3.1. Explanation
Shock absorbers must absorb or dissipate energy. One design consideration, when designing or choosing a shock absorber is where that energy will go. In most dashpots,
15

energy is converted to heat inside the viscous fluid. In hydraulic cylinders, the hydraulic fluid will heat up, while in air cylinders, the hot air is usually exhausted to the atmosphere. In other types of dashpots, such as electromagnetic ones, the dissipated energy can be stored and used later.

1.3.2. Description
Pneumatic and hydraulic shock absorbers commonly take the form of a cylinder with a sliding piston inside. The cylinder is filled with a fluid (such as hydraulic fluid) or air. This fluid filled piston/cylinder combination is a dashpot.

1.3.3. Applications
Shock absorbers are an important part of automobile and motorcycle suspensions, aircraft landing gear, and the supports for many industrial machines. Large shock absorbers have also been used in structural engineering to reduce the susceptibility of structures to earthquake damage and resonance.

Rear shock absorber and spring of a BMW R75/5 m

16

1.3.4. Vehicles suspension

In a vehicle, it reduces the effect of traveling over rough ground, leading to improved ride quality. Without shock absorbers, the vehicle would have a bouncing ride, as energy is stored in the spring and then released to the vehicle, possibly exceeding the allowed range of suspension movement. Control of excessive suspension movement without shock absorption requires stiffer (higher rate) springs, which would in turn give a harsh ride. Shock absorbers allow the use of soft (lower rate) springs while controlling the rate of suspension movement in response to bumps. They also, along with hysteresis in the tire itself, damp the motion of the un sprung weight up and down on the springiness of the tire. Since the tire is not as soft as the springs, effective wheel bounce damping may require stiffer shocks than would be ideal for the vehicle motion alone. Spring-based shock absorbers commonly use coil springs or leaf springs, though torsion bars can be used in torsional shocks as well. Ideal springs alone, however, are not shock absorbers as springs only store and do not dissipate or absorb energy. Vehicles typically employ springs or torsion bars as well as hydraulic shock absorbers. In this combination, "shock absorber" is reserved specifically for the hydraulic piston that absorbs and dissipates vibration.

1.3.5. Structures
17

Applied to a structure such as a building or bridge it may be part of a seismic retrofit or as part of new, earthquake resistant construction. In this application it allows yet restrains motion and absorbs resonant energy, which can cause excessive motion and eventual structural failure.

1.3.6. Types of shock absorbers

There are several commonly-used approaches to shock absorption:

Hysteresis (hysteresis is like a "memory" of the material, if you press down rubber disks, they tend to back to it's normal uncompressed state as the load of fingers is relieved of structural material, for example the compression of rubber disks, stretching of rubber bands and cords, bending of steel springs, or twisting of torsion bars. Hysteresis is the tendency for otherwise elastic materials to rebound with less force than was required to deform them. Simple vehicles with no separate shock absorbers are damped, to some extent, by the hysteresis of their springs and frames.

Dry friction as used in wheel brakes, by using disks (classically made of leather) at the pivot of a lever, with friction forced by springs. Used in early
18

automobiles such as the Ford Model T, up through some British cars of the 1940s. Although now considered obsolete, an advantage of this system is its mechanical simplicity; the degree of damping can be easily adjusted by tightening or loosening the screw clamping the disks, and it can be easily rebuilt with simple hand tools. A disadvantage is that the damping force tends not to increase with the speed of the vertical motion.

Solid state, tapered chain shock absorbers, using one or more tapered, axial alignment(s) of granular spheres, typically made of metals such as iron, in a casing.

Fluid friction, for example the flow of fluid through a narrow orifice (hydraulics), constitutes the vast majority of automotive shock absorbers. An advantage of this type is that using special internal valving the absorber may be made relatively soft to compression (allowing a soft response to a bump) and relatively stiff to extension, controlling "jounce", which is the vehicle response to energy stored in the springs; similarly, a series of valves controlled by springs can change the degree of stiffness according to the velocity of the impact or rebound. Specialized shock absorbers for racing purposes may allow the front end of a dragster to rise with minimal
19

resistance under acceleration, then strongly resist letting it settle, thereby maintaining a desirable rearward weight distribution for enhanced traction. Some shock absorbers allow tuning of the ride via control of the valve by a manual adjustment provided at the shock absorber. In more expensive vehicles the valves may be remotely adjustable, offering the driver control of the ride at will while the vehicle is operated. The ultimate control is provided by dynamic valve control via computer in response to sensors, giving both a smooth ride and a firm suspension when needed. Many shock absorbers contain compressed nitrogen, to reduce the tendency for the oil to foam under heavy use. Foaming temporarily reduces the damping ability of the unit. In very heavy duty units used for racing and/or off-road use, there may even be a secondary cylinder connected to the shock absorber to act as a reservoir for the oil and pressurized gas. Another variation is the Magneto rheological damper which changes its fluid characteristics through an electromagnet.

Compression of a gas, for example pneumatic shock absorbers, which can act like springs as the air pressure is building to resist the force on it. Once the air pressure reaches the necessary maximum, air dashpots will act like hydraulic dashpots. In aircraft landing gear air dashpots may be combined
20

with hydraulic damping to reduce bounce. Such struts are called oleo struts (combining oil and air) [3].

Magnetic effects. Eddy current dampers are dashpots that are constructed out of a large magnet inside of a non-magnetic, electrically conductive tube.

Inertial resistance to acceleration, for example prior to 1966 [4] the Citron 2CV had shock absorbers that damp wheel bounce with no external moving parts. These consisted of a spring-mounted 3.5 kg (7.75 lb) iron weight inside a vertical cylinder [5] and are similar to, yet much smaller than versions of the tuned mass dampers used on tall buildings

Composite hydro pneumatic devices which combine in a single device spring action, shock absorption, and often also ride-height control, as in some models of the Citron automobile.

Conventional shock absorbers combined with composite pneumatic springs with which allow ride height adjustment or even ride height control, seen in some large trucks and luxury sedans such as
21

certain Lincoln and most Land Rover automobiles. Ride height control is especially desirable in highway vehicles intended for occasional rough road use, as a means of improving handling and reducing aerodynamic drag by lowering the vehicle when operating on improved high speed roads.

The effect of a shock absorber at high (sound) frequencies is usually limited by using a compressible gas as the working fluid and/or mounting it with rubber bushings.

22

1.4. Spring
A spring is a flexible elastic object used to store mechanical energy. Springs are usually made out of hardened steel. Small springs can be wound from prehardened stock, while larger ones are made from annealed steel and hardened after fabrication. Some non-ferrous metals are also used including phosphor bronze and titanium for parts requiring corrosion resistance and beryllium copper for springs carrying electrical current (because of its low electrical resistance).
23

The rate of a spring is the change in the force it exerts, divided by the change in deflection of the spring. That is, it is the gradient of the force versus deflection curve. For an extension or compression spring it has the units of lbf/in, N/mm, or similar. For a torsion spring it has the units of Nm/rad or ftlbf/degree, for example. The inverse of spring rate is compliance, that is if a spring has a rate of 10 N/mm, it has a compliance of 0.1 mm/N. The stiffness (or rate) of springs in parallel is additive, as is the compliance of springs in series.

Helical or coil springs designed for tension

1.4.1. Theory
In classical physics, a spring can be seen as a device that stores potential energy by straining the bonds between the atoms of an elastic material. Hooke's law of elasticity states that the extension of an elastic rod (its distended length minus its relaxed length) is linearly proportional to its tension, the force used
24

to stretch it. Similarly, the contraction (negative extension) is proportional to the compression (negative tension). This law actually holds only approximately, and only when the deformation (extension or contraction) is small compared to the rod's overall length. For deformations beyond the elastic limit, atomic bonds get broken or rearranged, and a spring may snap, buckle, or permanently deform. Many materials have no clearly defined elastic limit, and Hooke's law cannot be meaningfully applied to these materials. Hooke's law is a mathematical consequence of the fact that the potential energy of the rod is a minimum when it has its relaxed length. Any smooth function of one variable approximates a quadratic function when examined near enough to its minimum point; and therefore the force which is the derivative of energy with respect to displacement will approximate a linear function.

1.4.2. Uses Vehicle suspension

25

Suspension is the term given to the system of springs, shock absorbers and linkages that connects a vehicle to its wheels. Suspension systems serve a dual purpose contributing to the car's handling and braking for good active safety and driving pleasure, and keeping vehicle occupants comfortable and reasonably well isolated from road noise, bumps, and vibrations. These goals are generally at odds, so the tuning of suspensions involves finding the right compromise. The suspension also protects the vehicle itself and any cargo or luggage from damage and wear. The design of front and rear suspension of a car may be different.

This article is primarily about four-wheeled (or more) vehicle suspension. For information on two-wheeled vehicles' suspensions see the suspension (motorcycle), motorcycle fork, bicycle suspension, and bicycle fork articles.

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1.5. ALTERNATOR

1.5.1. History
Alternating current generating systems were known in simple forms from the discovery of the magnetic induction of electric current. The early machines were developed by pioneers such as Michael Faraday and Hippolyte Pixii. Faraday developed the "rotating rectangle", whose operation was heteropolar - each active conductor passed successively through regions where the magnetic field was
27

in opposite directions. The first public demonstration of a more robust "alternator system" took place in 1886. Large two-phase alternating current generators were built by a British electrician, J.E.H. Gordon, in 1882. Lord Kelvin and Sebastian Ferranti also developed early alternators, producing frequencies between 100 and 300 hertz. In 1891, Nikola Tesla patented a practical "high-frequency" alternator (which operated around 15,000 hertz). After 1891, polyphase alternators were introduced to supply currents of multiple differing phases. Later alternators were designed for varying alternating-current frequencies between sixteen and about one hundred hertz, for use with arc lighting, incandescent lighting and electric motors.

1.5.2. Theory of operation

Alternators generate electricity by the same principle as DC generators, namely, when the magnetic field around a conductor changes, a current is induced in the conductor. Typically, a rotating magnet called the rotor turns within a stationary set of conductors wound in coils on an iron core, called the stator. The field cuts across the
28

conductors, generating an electrical current, as the mechanical input causes the rotor to turn. The rotating magnetic field induces an AC voltage in the stator windings. Often there are three sets of stator windings, physically offset so that the rotating magnetic field produces three phase currents, displaced by one-third of a period with respect to each other. The rotor magnetic field may be produced by induction (in a "brushless" alternator), by permanent magnets (in very small machines), or by a rotor winding energized with direct current through slip rings and brushes. The rotor magnetic field may even be provided by stationary field winding, with moving poles in the rotor. Automotive alternators invariably use a rotor winding, which allows control of the alternator generated voltage by varying the current in the rotor field winding. Permanent magnet machines avoid the loss due to magnetizing current in the rotor, but are restricted in size, owing to the cost of the magnet material. Since the permanent magnet field is constant, the terminal voltage varies directly with the speed of the generator. Brushless AC generators are usually larger machines than those used in automotive applications.
29

Synchronous speeds The output frequency of an alternator depends on the number of poles and the rotational speed. The speed corresponding to a particular frequency is called the synchronous speed for that frequency.

1.6. Rack and Pinion

A rack and pinion is a pair of gears which convert rotational motion into linear motion. The circular pinion engages teeth on a flat bar - the rack. Rotational motion applied to the pinion will cause the rack to move to the side, up to the limit of its travel. For example, in a rack railway, the rotation of a pinion mounted on a locomotive or a railcar engages a rack between the rails and pulls a train along a steep slope.
30

The rack and pinion arrangement is commonly found in the steering mechanism of cars or other wheeled, steered vehicles. This arrangement provides a lesser mechanical advantage than other mechanisms such as re-circulating ball, but much less backlash and greater feedback, or steering "feel". The use of a variable rack was invented by Arthur E Bishop,[1] so as to improve vehicle response and steering "feel" on-centre, and that has been fitted to many new vehicles, after he created a hot forging process to manufacture the racks, thus eliminating any subsequent need to machine the form of the gear teeth.

31

1.7. Battery
An electrical battery is one or more electrochemical cells that convert stored chemical energy into electrical energy.[1] Since the invention of the first battery (or "voltaic pile") in 1800 by Alessandro Volta, batteries have become a common power source for many household and industrial applications. According to a 2005 estimate, the worldwide battery industry generates US$48 billion in sales each year,[2] with 6% annual growth. There are two types of batteries: primary batteries (disposable batteries), which are designed to be used once and discarded, and secondary batteries (rechargeable batteries), which are designed to be recharged and used multiple times. Batteries come in many sizes, from miniature cells used to power hearing aids and wristwatches to battery banks the size of rooms that provide standby power for telephone exchanges and computer data centers.

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1.7.1. Principle of operation

A voltaic cell for demonstration purposes. In this example the two half-cells are linked by a salt bridge separator that permits the transfer of ions, but not water molecules. A battery is a device that converts chemical energy directly to electrical energy. It consists of a number of voltaic cells; each voltaic cell consists of two half cells connected in series by a conductive electrolyte containing anions and cations. One half-cell includes electrolyte and the electrode to which anions (negatively charged ions) migrate, i.e., the anode or negative electrode; the other half-cell includes electrolyte and the electrode to which cations (positively charged ions) migrate, i.e., the cathode or positive electrode. In the redox reaction that powers the battery, cations are reduced (electrons are added) at the cathode, while anions are oxidized (electrons are removed) at the anode. The electrodes do not touch each other but are electrically connected by the electrolyte. Some cells use two half-cells with different electrolytes. A separator between half cells allows ions to flow, but prevents mixing of the electrolytes. Each half cell has an electromotive force (or emf), determined by its ability to drive electric current from the
33

interior to the exterior of the cell. The net emf of the cell is the difference between the emfs of its half-cells, as first recognized by Volta. Therefore, if the electrodes have emfs and , then the net emf is ; in other words, the net emf is the difference between the reduction potentials of the half-reactions. The electrical driving force or across the terminals of a cell is known as the terminal voltage (difference) and is measured in volts. The terminal voltage of a cell that is neither charging nor discharging is called the open-circuit voltage and equals the emf of the cell. Because of internal resistance, the terminal voltage of a cell that is discharging is smaller in magnitude than the open-circuit voltage and the terminal voltage of a cell that is charging exceeds the open-circuit voltage.[27] An ideal cell has negligible internal resistance, so it would maintain a constant terminal voltage of until exhausted, then dropping to zero. If such a cell maintained 1.5 volts and stored a charge of one coulomb then on complete discharge it would perform 1.5 joule of work. In actual cells, the internal resistance increases under discharge, and the open circuit voltage also decreases under discharge. If the voltage and resistance are plotted against time, the resulting graphs typically are a curve; the shape of the curve varies according to the chemistry and internal arrangement employed.[28] As stated above, the voltage developed across a cell's terminals depends on the energy release of the chemical reactions of its electrodes and electrolyte. Alkaline and zinccarbon cells have different chemistries but approximately the same emf of 1.5 volts; likewise NiCd and NiMH cells have different chemistries, but approximately the same emf of 1.2 volts. On the other
34

hand the high electrochemical potential changes in the reactions of lithium compounds give lithium cells emfs of 3 volts or more.

1.7.2. Categories of batteries

Batteries are classified into two broad categories, each type with advantages and disadvantages.

Primary batteries irreversibly (within limits of practicality) transform chemical energy to electrical energy. When the initial supply of reactants is exhausted, energy cannot be readily restored to the battery by electrical means. Secondary batteries can be recharged; that is, they can have their chemical reactions reversed by supplying electrical energy to the cell, restoring their original composition.

Some types of primary batteries used, for example, for telegraph circuits, were restored to operation by replacing the components of the battery consumed by the chemical reaction. Secondary batteries are not indefinitely rechargeable due to dissipation of the active materials, loss of electrolyte and internal corrosion.

Chapter - 2 EXPERIMENTAL SETUP 2.1. Introduction

A regenerative shock absorber is a type of shock absorber that converts parasitic intermittent linear motion and vibration into useful energy, such as electricity.
35

Conventional shock absorbers simply dissipate this energy as heat. When used in an electric vehicle or hybrid electric vehicle the electricity generated by the shock absorber can be diverted to its power train to increase battery life. In non-electric vehicles the electricity can be used to power accessories such as air conditioning. Several different systems have been developed recently, though they are still in stages of development and not installed on production vehicles. The system is controlled by an active mechanical system that optimizes the damping, providing a smoother ride than conventional shocks while generating electricity to recharge the batteries or operate electrical equipment. During testing of a 6-shock truck, the MIT students found each shock absorber is able to generate up to an average of 1 kW on standard road, which is "enough power to completely displace the large alternator load in heavy trucks and military vehicles." If for some reason the electronics on the shocks fail, the fail-safe feature will have the shocks act simply like a normal shock absorber.

2.2. Mechanical Components 2.2.1. Shock Absorber Arrangement

The shock absorber is attached vertically to the frame so that the bumps or force can be applied to it with the help of a lever from the bottom. The shock absorber
36

selected is of a motorcycle and it is arranged in the same manner as done in a motorcycle. The diameter of the shock absorber body must be matched to the vehicle weight and intended use. Larger diameter shocks contain more oil for greater operating efficiency, as well as larger internal components and mounting hardware for strength. 2.0" Shocks are recommended for light weight vehicles (up to 5,000 lbs) and street applications. Multiple shocks per corner must be installed for heavier vehicles.
Kinematic Viscosity at 40C., cSt, Viscosity Index, Min. Flash Point, COC,C, Min. Pour Point, C, Max. 11.0 - 13.0 45 145 (-) 39

We are using shock absorber oil SAE-20 according to the project.

2.2.2. Rack & Pinion Arrangement

The rack is attached to the outer tube of the shock absorber. As the outer tube of the shock absorber moves up and down it give a reciprocatory motion to the rack which in turn rotates the pinion.
37

Then the pinion is coupled to the alternator which in turn rotates it and produces electricity. In our project following values of rack & pinion have been taken. Module = 1 Pressure angle = 20deg Teeth of pinion = 18 Pitch circle radius = 9mm Value of addendum = 1.0521mm Addendum radius of the pinion = 10.0521mm Radius of the pinion gear = 10mm In our project the rack moves 2.1= 54mm in one shock Teeth of Rack = 54 Max. path of contact to avoid interference = 5.433mm Pair of teeth in contact N = 1.84 Pair of teeth will always remain in contact whereas for 84% of time 2 pairs of teeth will be in contact.

2.3. Electrical Components 2.3.1. Alternator Arrangement

The alternator is directly coupled with the pinion. As the pinion rotates the alternator gets movement and produces
38

electricity. Therefore we have selected the alternator of following rating Vmax=12V

2.3.2. Battery Arrangement

The battery is connected with the alternator through wires to store the electricity produced. A 12V battery has been used in our project.

CHAPTER - 3 Design Process of Regenerative Shock Absorber

39

3.1. Introduction

A=ALTERNATOR B=ROD TO CONNECT WHEEL C=RUBBER SPRING/COVER TO PROTECT DUST E=SHOCKER ROD AREA D=RACK AND PINION GEAR ASSEMBLY G=WHEEL F=ELECTRICITY OUT FOR BATTERY CHARGING

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A regenerative shock absorber is a type of shock absorber that converts parasitic intermittent linear motion and vibration into useful energy, such as electricity. Conventional shock absorbers simply dissipate this energy as heat. When used in an electric vehicle or hybrid electric vehicle the electricity generated by the shock absorber can be diverted to its power train to increase battery life. In non-electric vehicles the electricity can be used to power accessories such as air conditioning. Several different systems have been developed recently, though they are still in stages of development and not installed on production vehicles. The system is controlled by an active mechanical system that optimizes the damping, providing a smoother ride than conventional shocks while generating electricity to recharge the batteries or operate electrical equipment. During testing of a 6-shock truck, the MIT students found each shock absorber is able to generate up to an average of 1 kW on standard road, which is "enough power to completely displace the large alternator load in heavy trucks and military vehicles." If for some reason the electronics on the shocks fail, the fail-safe feature will have the shocks act simply like a normal shock absorber. In the above structure, a modified design is shown for the shocker motion provided by Rack and Pinion Gear Assembly that generates power. The motor(generator) will operate clock and anti-clock to operate as it sense the pot holes or bumps on the road. The shocker rod activates the rack and pinion up and down motion that run the motor
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(generator) in clock and anti-clock motion.

3.2. Selection of Shock Absorber

3.2.1. Shock Absorber Dia.
The diameter of the shock absorber body must be matched to the vehicle weight and intended use. Larger diameter shocks contain more oil for greater operating efficiency, as well as larger internal components and mounting hardware for strength.

2.0" Shocks are recommended for light weight vehicles (up to 5,000 lbs) and street applications. Multiple shocks per corner must be installed for heavier vehicles. 2.5" Shocks are recommended for medium weight vehicles (5,000 7,500 lbs) and recreational or racing applications. A single 2.5" shock is comparable in performance to dual 2.0" shocks. 3.0" Shocks are recommended for heavy weight vehicles (over 7,500 lbs) and professional racing applications. A single 3.0" shock is comparable in performance to dual 2.5" shocks.

3.2.2. Piston Rod Diameter

The piston rod diameter should be matched to the desired duty rating. A larger diameter rod will provide greater resistance to compression forces, although
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cost and weight will also increase.

5/8" Diameter rods are the standard size for most 2.0" shocks, and recommended for light-duty and street applications. 7/8" Diameter rods are optional for most 2.0" shocks and standard for all 2.5" designs excluding air shocks. The 7/8" rod is best suited for street and medium-duty off-road applications. 1" Diameter rods are standard on all 3.0" and 3.75" shocks, and ideal for heavy-duty off-road applications and extreme terrain. 1-1/4" Diameter rods are only available on 2.0" air shocks and hydraulic bump stops. 1-5/8" Diameter rods are only available on 2.5" air shocks.

3.2.3. Shock Absorber Oil Specification

CHARACTERISTICS
Kinematic Viscosity at 40C., cSt, Viscosity Index, Min. Flash Point, COC,C, Min. Pour Point, C, Max.

SAE-20
11.0 - 13.0 45 145 (-) 39

SAE-30
17.0 - 19.0 45 160 (-) 36

We are using shock absorber oil SAE-20 according to the project.

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44

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3.2.4. Thrust Force Calculation

a. Colliding object mass M=50kg b. Colliding speed V=1.0m/s c. Cylinder thrust F= /4 X 50mm X 50mm X 0. 5MPa=981.7N
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3.2.5. Calculation of Total Energy

a. Kinetic energy: E1=1/2MV^2= 1/2X 50 kg X 1.0^2 [m/s] =25(J) Select NCK-2.6(Emax=26J) (St=15mm), since E1achieved=25J b. Thrust energy: E2=F X S=981.7 X 0.015m=14.7 [J] c. All absorbed energy: E= E1+E2= 25 [J]+14.7[J]= 39.7[J] Recalculate with one size larger NCK-7, since this E=39.7[J] cannot be absorbed by temporarily selected NCK-2.6. b'.E2=FX S=981.7 [N] X 0.02 [m]=19.6[J] c'. E=E1+E2=25 [J]+19.6[J]=44.6[J] Go to confirmation of colliding object equivalent mass, since this E=44.6 [J] can be absorbed by NCK-7.

Check Colliding Object Equivalent Mass

a. Colliding object equivalent mass Me= 2E/V^2 =2x44.6/1^2=89.2kg b. NCK-7 Me is 150 [kg], so this is larger than calculated colliding object equivalent mass. Therefore, use NCK47

7under these conditions.

3.2.6. Flow Chart for Selection

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3.3. Design of Rack & Pinion

3.3.1. Module
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Minimum the module less the rack travels for a rotation of pinion. Lower load requires low module. Taking module = 1 Pressure angle = 20deg Minimum no. of teeth for pinion for avoid interference t(min) = 2k / sin^2 k = 1 (standard addedum = 1) t(min) = 2 1/ sin^2 20 t(min) = 17.1 or 18 Teeth of pinion = 18 Pitch circle radius r = mt/2 = 118/2 r = 9mm To avoid interference, max. Value of addendum = r sin^2 = 9 sin^2 20 = 9 0.1169 = 1.0521mm Addendum radius of the pinion = 9 + 1.0521 = 10.0521mm
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Radius of the pinion gear = 10mm No. of teeth of rack. In our project the rack moves 2.1= 54mm in one shock As dia of the rack is infinite, the pinion will move on length, so it will consider as the dia. m=D/T m=1 D = T , T = 54 No. of teeths in contact at meshing Max. path of contact to avoid interference. = ra^2 (rcos)^2 = (10.0521)^2 (9cos20)^2 = 101.0447 71.524 = 29.5199 = 5.433mm Pair of teeth in contact N = arc of contact / circular pitch = (path of cont. / cos) 1/m = (5.433 / cos20) 1/3.14 = 5.7819 / 3.14 = 1.84

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Thus 1 pair of teeth will always remain in contact whereas for 84% of time 2 pairs of teeth will be in contact.

3.4. Selection of Alternator

The main advantage of alternator is that it can generate electric power at lower R.P.M. Therefore we have selected the alternator of following rating Vmax=12V

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CHAPTER - 4 FABRICATION

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Steps of fabrication:1.Market survey and components purchasing. 2.Wooden frame acc. to shocker size. 3.Fixing of shocker in wooden frame. 4.Fixing and adjusting rack and pinion unit acc. to shocker motion. 5.Joining pinion shaft with alternator shaft through gear train.
6. 7.

Taking output from alternator through wires. Connecting multimeter, L.E.D and battery to alternator through output wires.

8.Placing switches for operating above appliances. 9.Prepare wooden lever for giving the motion to shocker.

CHAPTER 5 COLNCLUSION

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The following conclusions have been derived: It is an object of the invention that can be used simultaneously as a generator and a shock absorber. It is another object of the invention to provide a system for converting axle vibration into electricity which can charge a battery. The main objective of this project is to increase battery power in Hybrid cars.

The related research on this project concludes that:

RSA improves fuel efficiency up to 2-10%.

In normal driving condition it generates 2-8W electric power per wheel. The power it generates is proportional to the sq. of the magnetic flux across the coil.

REFRENCES

Engg. Mechanics By John Robert

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Taylor

REGENERATIVE SHOCK ABSORBER By Prof. Amarnath Kaushik J & Ankit Mehta

Shock Absorber Selection Guide By Shakun Shrivastava

WWW.WIKIPEDIA.COM WWW.PHYSORG.COM WWW.GIZMAG.COM WWW.MIT.EDU

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